The present invention relates to a power actuator for a machine element such as a clutch, a variable speed change device or a brake.
In a known power actuator of the foregoing kind there is provided a housing in which are mounted a motor-driven worm gear and an actuating shaft adapted to control the operative condition of the machine element, that is, engagement or disengagement in case of a clutch or a brake or a greater or lesser speed ratio in the case of a variable speed change device. Such a power actuator also comprise motion transmitting means between the worm gear and the actuating shaft comprising gear means rotatable inside the housing and a sector gear arranged inside the housing and fixed for angular movement with the actuating shaft, the gear means cooperating with the worm gear, with the sector gear and with a force moderating spring attached to the housing.
In general such a power actuator has produced excellent results in as much as the presence of power output of the motor is reduced by means of the force moderating spring. Further, the entire power actuator as described above which comprises a worm gear, gear means and a sector gear is both simple and robust and is entirely satisfactory in operation.